An information recording device is essential to any information processing system. In the field of information recording with such systems, magnetic recording is the main stream, since it is now supported by fair technical advance which has so far been made, it is less expensive than other recording methods, and it offers nonvolatile recording.
In recent years, there have been increasing demands for higher density and higher capacity for magnetic recording media. To meet these demands, it is necessary to obtain:
(1) excellent surface smoothness for reduced spacing loss; and PA0 (2) excellent dispersibility and high packing density of magnetic powder for increased output. PA0 (1) The magnetic layer should have excellent abrasion resistance. PA0 (2) The magnetic layer surface is not contaminated with stain, dust or other contaminants.
Meanwhile, there will be increasing demands for improved durability and reliability with the increase in the capacity of recording media. For these improvements, some special features including the following are needed.
Such magnetic recording uses a floppy disc, for instance, which comprises a disc-shaped magnetic recording medium, having a magnetic layer containing a magnetic powder and a binder, and a medium cleaning liner, in contact with the magnetic layer described above, both housed in a casing. The liner described above generally comprises a nonwoven fabric, e.g., rayon braided member tied with thermoplastic polypropylene, and its periphery is joined to the inside of the casing by hot melt adhesion or ultrasonic melt adhesion.
However, conventional nonwoven fabrics made mainly of rayon show considerable detachment of resin powder and fluff, though their cleanability is relatively good. If a non-rayon component for the prevention of this phenomenon, e.g., polyester fiber or polypropylene is increased, the cleanability is degraded or the magnetic layer is damaged, and drop-out increases.
Also, despite the increasing demands for higher density, higher output and higher durability of floppy discs, there have been no known binders which are sufficiently dispersible in fine grains of magnetic powder, and it has been difficult to obtain high density and high durability.